The credit card processing company for Neiman Marcus informed the retailer in mid-December about a possibility of customers experiencing unauthorized payment card activity after making purchases at Neiman Marcus Group stores.

Neiman Marcus began investigating and on January 1 confirmed that the company was indeed the victim of a criminal cyber-security breach. The hacking event means an undisclosed number of customers’ cards were possibly compromised.

A statement sent out by Neiman Marcus said, in part –

“We informed federal law enforcement agencies and are working actively with the U.S. Secret Service, the payment brands, our credit card processor, a leading investigations, intelligence and risk management firm, and a leading forensics firm to investigate the situation.”

Neiman Marcus claims to have made progress containing the breach and say they have taken steps to enhance information security.

The company said it is taking steps to notify customers with credit cards that have definitely been used fraudulently after making a Neiman Marcus purchase.